Overthrow-check for calculating-machines



J. F. MAYS. OVERTHROW CHECK FOR CALCULATING MACHINES. APPLICATION FILEDJUNE 24. 918.

1,315,144. PatentedSept.2,1919.

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J. F. MAYS.

OVERTHROW CHECK FOR CALCULATING MACHINES.

APPLICATION FILED .IUNE 24.19I8.

Patented Sept. 2, 1919.

3 SHEETSSHEET 2.

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J. F. MAYS.

OVERTHROW CHECK FOR CALCULATING MACHINES. APPLICAHON mzp JUNE 24.1918.

1 ,3 1 5, 1 44. Patented Sept. 2, 1919.

3 SHEETSSHEET 3.

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UNITED STATES PATENT OFFICE.

JAMES F. MAYS, F BIRMINGHAM, ALABAMA, ASSIGNOR T0 MAYS ACCOUNTINGMACHINE COMPANY, OF LEXINGTON, NORTH CAROLINA, A. CORPORATION OF NORTHCAROLINA.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed June 24, 1918. Serial No. 241,523.

useful Improvements in Overthrow-Checks for Calculating-Machines, ofwhich the following is a specification.

This invention relates to improvements in calculating or adding machinesand the like and it pertains more especially to the dial actuatingmechanism thereof. The primary object of the invention is to providenovel and improved means for effectively preventing overthrow or excessmotion of the dials when the same are rotated or advanced incidental tothe calculating or adding operation, whereby accurate registration ofthe numerals on the dials with the openings through which they show isattained, cor rect operation of the ratchet mechanisms through which thedials are actuated is insured, and each dial is permitted to advance ateach operation only to the point corresponding to the number advancedinto the dial, this feature being particularly advantageous wherea'printing attachment is employed in association with the dial as itenables all the characters in printing position on the differentprinting wheels to be alin d properly.

To these ends, the invention comprises an overthrow check including apawl and a cooperating toothed wheel, the latter being fixed to therespective dial, said pawl and wheel being normally disengaged to permita carry to be made into such dial from the dial of lower denomination,the pawl, however, being automatically engaged with the toothed wheel inresponse to the initial part of the dial driving movement of the dialactuating mechanism, whereby overthrow of the dial, when it has beenrotated or advanced to the proper point, due to momentum, is prevented,the pawl being auto matically disengaged from the toothed wheel uponreturn of the dial actuating mechanism to normal position. Cooperativewith the overthrow check for the dial is means for automaticallyarresting the dial driving motion of the dial driving mecha nism, suchmeans being operative coincident with the action of said check inpreventing overthrow of the dial, in consequence of which the dialdriving motion of the dial actuating mechanism is arrested at the momentthe dial is checked, and hence the momentum of the mechanism throughwhich the dial is actuated is prevented from acting upon the dial with atendency to cause overthrow thereof.

The invention is applicable to calculating and adding machines ofdilferent types, and it is especially applicable to those of the classwherein the dials are actuated by the direct down strokes of the keysand the initial parts of such strokes serve to cause the carrymechanisms for the dials to be held from operation, a machine of thisclass being shown and described in my copending application, Serial No.148,559, filed February 14, 1917, and the preferred mechanism forcontrolling the operation of the carry mechanism being shown anddescribed in my copending application, Serial No. 214,717, filed January31, 1917.

The preferred embodiment of the invention is shown in the accompanyingdrawings and will be hereinafter described in detail. It is to beunderstood, however, that the invention is not restricted to the preciseconstruction shown, as equivalent constructions are contemplated andwill be included within the scope of the claims.

In the accompanying drawings:

Figure 1 represents a longitudinal vertical section through acalculating machine embodying an overthrow check constructed inaccordance with the present invention, one unit only being shown forclearness in illustration.

Fig'. 2 is a side elevation, on an enlarged scale, of the overthrowcheck and the part of the dial driving'mechanism by which it iscontrolled.

Fig. 8 represents an end elevation of the overthrow check as viewed fromthe right in Fig. 2. i

Fig. 1 represents a section on the line 4t-4: of Fig. 2 and looking inthe direction of the arrow.

Fig. 5 represents a section taken longitudinally through the overflowcheck and associated mechanism shown in Fig. 2.

Fig. 6 represents a transverse section through the common rock shaft forthe column of keys showing one of the keys cooperative therewith.

Fig. 7 is an elevation of the key shown in Fig. 6 as viewed from theright.

Fig. 8 is a detail view showing three of the keys and the overthrowmechanism controlled thereby as viewed from the opposite side from whichthese parts appear in Fig. 1. Figs. 9 and 10 represent transversesections through the common rock shaft for the column of keys, thesections being taken at different planes longitudinally of such shaftand showing the differential angular spacing of the overthrow stopsthereon fordiffcirent keys.

Fig. 11 represents a section on the line 11-- 11 Fig. 5, looking in thedirection of the arrow.

The present invention is shown in the present instance as applied to acalculating machine of the class shown and described in my application,Serial No. 148,559 hereinbefore referred to, one unit only of themachine being shown in the present instance and reference being made tosaid applicati on for a full and complete disclosure of the machine. Asshown, 1 designates the casing of the machine which contains the variousmechanisms, 2 designates the keys of the column for the respective unit,these keys being reciprocable vertically through the top of the casing,these keys having buttons on their upper ends bearing numbers readingfrom 1 to 9 inclusive, the button bearing the number 1 being located atthe left-hand end, Fig. 1, and the button bearing the numher 9 beinglocated'at the right-hand end of said figure. The keys bearing thenumbers 1, 2 and 3 are operatively connected to key levers 3 and thekeys bearing the numbrs 4t, 5 and 6 are operatively connected to the keylevers 1, the key levers 3 and l being operative upon a suitably steppedcrossmember 5 which is carried by a bar 6, the latter being guided toreciprocate vertically within the casing and is provided with means foroperatively connecting it to a rock shaft common to all the key bars, aswill be hereinafter described. The key levers 3 and 4 are differentiallypivoted in the casing in the manner and forthe purposes described in myapplication Serial No. 148,559. The keys bearing the numbers 7, 8 and 9are without key levers, these keys having a direct action upon thecommon rock shaft. The common rock shaft 7 is journaled in suitablesupports 8 and 9 within the casing and it has fixed thereto toothedpinions 10 and 11, the keys corresponding to the numerals 7, 8 and 9having toothed racks 12 thereon which are adapted to mesh with therespective pinions 10, and the bar 6 whichis common to the keys bearingthe numbers 1- 6 inclusive carries a toothed rack 13 which is adapted tocotiperate with the pinion 11 on the common shaft. An arm 1% is fixed tothe shaft 7 in proximity to each pinion thereon and a pin or projection15 is located at one side of each rack 12 or 13 and is adapted to bearagainst the respective arm 14-. In consequence, descent of any one ofthe keys bearing the numbers 7, 8 and 9 or the bar 6 which is common tothe keys hearing the numbers 1 to 6 inclusive will initiate rotation ofthe shaft 7 through the action of the respective pin 15 on thecorresponding arm 14L, and continued descent of such key or bar willfurther rotate the shaft 7 through the action of the rack 12 or 13, asthe case may be, upon the respective pinion 10 or 11. The shaft 7 isrotated differentially in conformity with the particular key which isactuated as explained in my copending application, Serial No. 118,559,it being understood that one of these shafts 7 is provided for eachcolumn of keys comprising a unit of the machine and that any desirednumber of units may be used. The shaft is restored to normal positionafter each actuation thereof by a spring 16 and each key is restored toits normal elevated position by a spring 17 The dial 18 for each unit isfixed to a dial shaft 19, the latter being mounted in suitable bearings20 and 21 arranged within the casing and, in the present instance, thetop of the casing is provided with a sight opening 22 through which eachnumeral on the dial is visible as such numeral is advamed into operativeposition. The carry mechanism for carrying a numeral into this dial fromthe dial of the next lower denomination is shown generally and itcorresponds to that shown and described in my copending application,Serial No. I l-8,559, to which reference is made for a full. descriptionthereof, this carry mechanism being controlled by a cam 24 fixed on theshaft 7 and cooperative with a roller 25, the latter being carried by alever 26 which is pivoted at 27 to a station ary bracket 28, and thefree end of the lever 26 is connected to the carry control. mechanism bya link 29.

The dial fixed on the dial shaft 19 is driven through a ratchetmechanism 36. This ratchet mechanism comprises an internally tootheddriven member 31 which is fixed to the dial shaft 19, a driving member32, and a pawl 33, which pawl is carried by the driving member 32 and isarranged to cooperate with the ratchet teeth of the driven member 31,the pawl being operative upon such teeth during advancing movement ofthe driving member 32 and the pawl riding idly over the teeth of thedriven member 31 during return movement of the driving member 32. Thedriving member 32, as shown, is fixed to a sleeve 34 which is revolubleOn the dial shaft 19, and a second sleeve v 35 is fitted revolubly overthe sleeve 34, the

outer sleeve 35 having a pinion 36 fixed thereon. The pinion 36 mesheswith and is actuated by atoothed sector 36 which is fixed on the shaft 7of the respective unit, motion imparted to this shaft 7 throughactuation of the keys being transmitted to the respective dial throughthe medium of the pinion 36 and the ratchet and pawl mechanism 31, 32and 33.

The overthrow check for preventing excess motion of the dial is alsoapplied in the present instance to a machine of the class disclosed inmy copending application, Serial No. 148,559, wherein the initial partof the down stroke of any key is utilized to lock the carry mechanismfrom operation and it is further applied to a mechanism such as thatshown and described in my' copending application, Serial No. 214,717,whereby lost or idle motion is afforded the dial driving pinion 36 inresponse to the initial part of the down stroke of a key and the carrymechanisms may be locked before advance of any dial commences.Preferably, and as shown in the present embodiment of the invention,this preliminary lost or idle motion of the pinion which permitsactuation of the carry control mechanism is utilized to actuate theoverthrow check for the dial. In the construction shown, the overthrowcheck for the dial comprises a toothed wheel 37 which is fixed to thedial shaft 19, this wheel being provided with ten peripheralequidistantly spaced teeth 38 which correspond in number and location tothe numerals on the dial, a disk or other suitable member 39 which isfixed to the sleeve 34 to which the driving member 32 of the ratchetmechanism is fixed, a pawl 40 which is pivoted at 41 to the disk 39 andhas a tooth or projection 42 arranged to engage the advance side of anyone of the teeth 38 on the wheel 37 a pin 43 being fixed to the pawl andextending through a slot 44 in the disk 39, and a d1sk or otherappropriate member 45, the latter being fixed to the outer sleeve 35 towhich the pinion 36 is fixed, this disk 45 being formed with a cam slot46 into which the pin 43 projects. A suitable spring 47 acts on the pawl40 with a tendency to disengage it from the toothed wheel 37 and tonormally hold the pawl in such position, the move ment of the pawl 40under the influence of the spring 47 being limited by engagement of thepin 43 with the outer end of the slot 44. The cam slot 46 in thedisk 45has a cam surface 48 formed on its outer edge, the pin 43 being arrangedto cooperate with this cam surface. The pinion 36 is capable of limitedangular movement relatively to the ratchet driving member 43, the pinionbeing connected to the member 32 through the medium of a spring .49 oneend of which is attached to a pin 50 which is fixed to the pinion andthe other end of which is attached to a pin 51, the latter pin extendingthrough a circumferential slot 52 formed in the pinion and being fixedto the member 32. As shown and described in my copending application,Serial No. 214,717, the spring 49, when the pinion is in normalposition, acts to rotate the pinion in the direction indicated by thearrow in Fig. 11 and to also rotate the member 32 in a reversedirection. Such reverse rotation of the member 32 is limited by theengagement of the stop 53 on the member 32 which rest-s against a fixedstop 54. The pinion is ro tated in the direction of the arrow (Fig. 11)in response to the down stroke of any one of the keys of the columnbelonging thereto. The initial part of such rotation of the pinioncauses the pin 51 to recede toward the opposite end of the slot 52 inconsequence of which the member 32 will be idle or will remainstationary during this advance rotation of the pinion. As a result, thedisk 39 which is fixed to the member 32 will remain stationary duringthis advance rotation of the pinion while the disk 45 will rotate duringthis advance movement of the pinion, in consequence of which the camsurface 48 formed on the outer edge of the slot 46 in the disk 45 willact upon the pin 43 attached to the pawl 40 and will cause the pawl 40to move inwardly, bringing its tooth or projection 42 into engagementwith the advance side of the adjacent tooth 38 on the wheel 37 When thepreliminary or advance movement of the pinion has been completed, thecontinued descent of the key causes the member 32 to advance in unisonwith the pinion 36 as a result of the engagement of the right hand endof the slot 52 with the pin 51, the pinion and the driving member 32 ofthe ratchet mechanism then advancing in unison, the dial being ad vancedthrough the medium of the ratchet mechanism, and, also, the disks 39 and45 will advance in unison with the pinion 3G and the member 32. Thetoothed wheel 37 which advances in unison with the dial and is fixed tothe dial shaft is held by the pawl 40, in consequence of which rotationof the dial through an angle or arc greater than that through which thepinion 36 and ratchet driving member 32 advance is prevented.

Overthrow or excess motion of the keyoperated dial actuating mechanismwhich acts upon the pinion 36 is also prevented. In the constructionshown for accomplishing this purpose, the shaft 7 which is common to allthe keys of the respective column is provided with graduated 01'differentially spaced stop arms which are arranged to coiiperate withstops, such stops being controlled by the respective keys of the columnwhereby the shaft 7 is permitted to rotate only through an anglecorresponding to the extent of advance which is to be imparted to thedial by the respective key. In the present instance, a series of radialarms 55 is fixed to the shaft 7, these arms being located beside therespective key bars, and these arms are set at different angles withrespect to the axis of the shaft 7 according to the extent of rotationwhich is to be imparted to such shaft by the different ke s. The guide56 through which the lower ends of the key bars operate is preferablyangleshaped in cross-section, the upstanding flange 57 thereof havingextensions 58 projecting from its upper edge, the upper edge of eachprojection being curved, as shown at 59, and these upstandingprojections 58 are located immediately beside the paths of therespective stop arms 55. A set of stops shown in the form of levers 60are pivoted at 61 to the upstanding fig nge 57, the upper end of eachstop being bent laterally to form a foot 62 which overlies the upper endof the respective projection 58, the lower end 63 of each stop beingbent laterally, as shown, and arranged to cotiperate with a bevel orother ca-m surface 6% at or adjacent to the lower end of the respectivekey bar. A spring 65 operates with a tendency to pull the foot 62 ofeach stop out of the path of the respective stop arm 55, a pin 66limiting the movement of the stop in such direction. Normally, with allof the keys in elevated position, the stops 60 are in the position shownin Fig. 8, the feet 62 thereon being then clear of the paths of therespe'0 tive stop arms 55. However, depressionpf any key causes the camor bevel 64, during the initial part of such movement, to deflect theend 63 of the respective stop 60, thus bringing the foot 62 on the upperend of the stop into the path of the respective stop arm 55, the foot 62remaining in such position during the continued descent of the key, andhence the stop arm 55 corresponding to the depressed key will come intoengagement with the foot 62 when the key has been depressed to theproper limit of its stroke. Owing to the differential connections of thedifferent keys to the shaft 7, th latter will be rotated through'difierent angles upon depression of the different keys, and it will. beunderstood that the stop arms 55 are set at different angles or spacedcircumferentially of the shaft 7 to conform with the different ranges ofadvance imparted to the shaft 7 by the different keys. Owing to the rackand pinion connections between the key bars and the shaft 7, the keybars as well as the shaft 7 will be arrested in their movements whensuch parts have been actuated to the proper extent, and henceover-motion of either the shaft 7 or the key bars cannot occur, inconsequence of which over-motion cannot be transmitted from the shaft 7through the sector 36 to the pinion 36.

In the direct key-operated type of machine to which the invention isshown applied in the present instance, all the stops for the commonactuating shaft will be normally in inoperative position while the keysare in their normal raised position and, also, the pawl and toothedwheel of the overn1otion check for the dial will be disengaged. Theinitial part of the down stroke of any key of the respective columnwill, however, set the stop individual to such key in position to arrestrotation of the shaft at the proper point corresponding to the extent ofrotation which is to be imparted to the shaft by such key, and,coincident-1y, such initial part of the down stroke of the key willengage the pawl with the toothed wheel of the over motion check for thedial. This initial part of the down stroke of the key also effectslocking of the carrying mechanisms for the dials, as will 'be understoodfrom the hereinbeforementioned applications, the dial remainingmotionless during such period owing to the lost motion connectionbetween the pinion and the dial actuating ratchet mechanism. Continuedmotion in the depression of the key effects advance of the respectivedial to an extent corresponding to the numeral represented by theparticular key which has been depressed, the appropriate stop arrestingmotion of the shaft and the key connected thereto when such key has beendepressed to the proper extent and the pawl and toothed wheelconcurrently arresting rotation of the dial when the latter has beenadvanced to the proper extent in accordance with the key which 5 hasbeen depressed. Release of the depressed key permits the same and theactuating shaft connected thereto to return to normal position and,simultaneously, the pinion and dial actuating ratchet mechanism returnto 1 normal position, the movement of the pinion toward normal positionbeginning immediately at the commencement of the return movement of thekey and preceding the commencement of the return movement of 11 theratchet mechanism, and during this relative movement between the pinionand ratchet mechanism, the pawl of the overmotion check is caused todisengage from its coiiperating toothed wheel, and during 0 the finalpart of the return movement of the key, the stop corresponding to thedepressed key returns to its normal inactive position and the carrycontrol mechanism is released or unlocked, thus permitting a carry to bemade into the dial if such carry is due.

The means provided by the present invention for preventing over-throw orexcess advance of the dial is relatively simple and compact in itsconstruction, it may be easily applied to the machine, this beingespecially so when it is applied to machines of the' class shown in thepresent instance where it utilizes the lost motion connection betweenthe dial and its actuating pinion for setting the dial check into andout of operative position, it is certain in its operation, and it doesnot impair the speed and facility of operation of the machine.

The means provided by the present invention for preventing overthrow isparticularly adapted for use in a calculating machine wherein the dialsare actuated or advanced directly by the downstrokes of the keys. Insuch machines, the dials have a marked tendency to overthrow, this beingespecially true when the 7 8 and 9 keys are operated, at which times thedials are rotated through relatively large angles and at high velocity.The overthrow checki herein provided, however, fulfil the conditionsimposed upon it in a machlne of the type referred to for the reasonsthat the dial and its actuating means are concurrently checked atdifferent points between the keys and the dials, and that the overthrowchecks for the dials and also the actuating mechanisms therefor are set1n operative position in response to the initial part of the dialactuating stroke of the key and before the dial commences to advance inresponse to such key stroke, certamty 1n the operations of the overthrowdevices being thereby insured, even though the keys may be actuatedquickly and in repetition.

I claim as my invention 1. In a calculating machine, a dial, actuatingmechanism therefor, an overthrow check, and means for settingsaid check1n position to prevent excess mot1on of the d1al prior to advance of thedial by said actuating mechanism and for holdmg the check in suchposition during the advance of the dial.

2. In a calculating machine, a numeral wheel, actuating mechanismtherefor, an overthrow check for preventing excess motion. of thenumeral wheel incident to its advance, and means for setting saidoverthrow check in active condition by the inltial operation of saidactuating mechan sm and for holding the check in such condition duringthe advance of the numeral wheel.

3. In a machine of the class described having a numeral wheel andactuating mechanism therefor, an overthrow check movable into and out ofposition to prevent excess motion at the termination of the advance ofthe numeral wheel, and means for automatically setting said check inoperative position by the initial part of the operation of the actuatingmechanism and prlor to the advance of the numeral wheel andfor-positively holding the check in such position during the advance ofthe numeral wheel.

4. In a machine of the class described, a

means for setting said check in operative position during saidpreliminary movement of the dlal advancing means.

6. In a machine of the class described, a

dial, actuating means therefor movable in one direction to advance thedial and capable of a return movement, said actuating means having anidle movement preliminarily to its dial actuating movement and alsoduring its return movement, and an overthrow check set in operation toprevent excess advance of the dial during said preliminary idle movementof the actuating means and set in inoperative position during the returnmovement of the actuating means.

7 In a machine of the class described, a

' dial, actuating means therefor movable in one dlrection to advance thedial and capable of a return movement, said actuating means havmg idlemovements relatively to the dial preliminarily to its dial advancing andreturn movements respectively, an overthrow check for preventing excessmotion in the advance of the dial, and means'for setting said check inoperative position during the preliminary idle movement of the actuatingmeans prior to the advance of the dial and for rendering the checkinoperative during the idle movement of the actuating meanspreliminarily to its return.

8. In a calculating machine having a dial, a key, and actuating meansresponsive to a down stroke of the key to advance the dial, a member forconnecting together the dial and its actuating means to prevent excessmotion in the advance of the dial, and means for setting said member inoperative position prior to the commencement of advance of the dial.

9. In a calculating machine having a dial, a key, and actuating meansresponsive to a down stroke of such key to cause advance of the dial, amember for locking together the dial and its actuating means to preventex-v cess advance motion of the dial, and means for setting said memberin operative position prior to the advance of the dial in response tothe down stroke of the key and for rendering said member inoperative inresponse to the return stroke of the key.

10. In a machine of the class described, a

dial, actuating means for advancing it, said actuating means beingcapable of motion relatively to the dial preliminarily to its dialadvancing movement, a toothed wheel fixed to move with the dial, a pawlcarried by an operative part of the dial actuating means and arranged tocooperate with such wheel, and means operative during said preliminaryadvance movement of said actuating means to set said pawl in cooperativerelation with said toothed wheel.

11. In a machine of the class described, a rotatable dial, a toothedwheel connected to turn therewith, a dial actuating pinion having a lostmotion connection with the dial, a pawl adapted to engage and disengagerelatively to said toothed wheel, and means operative in consequence ofthe lost motion between the pinion and dial for setting said pawl inengagement with said toothed wheel prior to the advance of the dial.

12. In a machine of the class described, a rotatable dial, a toothedwheel fixed to rotate with the dial, a dial actuating pinion capable oflimited rotation relatively to said dial and also connected to rotatewith the dial to advance it, a pawl adapted to cooperate with saidtoothed wheel to prevent overthrow of the dial in its advance, and meansoperative by said relative movement between the pinion and dial forsetting said pawl in cooperative relation with said toothed Wheel.

13. In a machine of the class described, a rotatable dial, ratchet dialdriving mechanism comprising a driving member rotatable relatively tothe dial and a driven member connected to rotate with the dial,actuating means for advancing the dial including a pinion having a lostmotion connection with the driving member of the ratchet mechanism, atoothed wheel connected to rotate with the dial, a member connected toturn with said driving member of the ratchet mechanism and carrying apawl adapted to,

cooperate with said toothed wheel, and means operative in consequence ofthe lost motion between said pinion and dial for controlling therelation between said pawl and toothed wheel.

14. In a machine of the class described, a rotatable dial, ratchet dialdriving mechanism comprising a driving member rotatable relatively tothe dial and a driven member connected to rotate with the dial,actuating means for advancing the dial including a pinion having a lostmotion connection With the driving member of the ratchet mechanism, atoothed wheel connected to rotate with the dial, a member connected toturn with said driving member of the ratchet mechanism and carrying apawl adapted to cooperate with said toothed wheel, and a memberconnected to rotate with the pinion and having a cam cooperative withsaid pawl to control the engagement of the pawl ,corresponding to thedifferent keys of the with said toothed wheel in consequence of saidlost motion between the pinion and dial.

15. In a calculating machine, a dial, a column of keys, means operativein response to a down stroke of one of such keys to advance the dial,means for preventing overthrow of such key and dial operating meansincident to the down stroke of the key, and means operative coincidentlyto set said overthrow means in condition to connect together the dialand its operating means and thus prevent overthrow of the dial.

16. In a calculating machine, a dial, actuating keys, means operative inresponse to the down stroke of a key to advance the dial, means set bythe initial part of the down stroke of the key to prevent overthrow ofsaid dial advancing means, and means also set by the initial part of thedown stroke of the key to prevent overthrow of the dial.

17 In a calculating machine, a dial, a column of actuating keys, dialactuating means operative differentially in response to the down strokesof the different keys to advance the dial, means set by the initial partof the down strokes of the respective keys for preventing overthrow inthe operation of said dial actuating means, and means cooperative withthe dial and also set by the initial part of the down stroke of therespective keys for preventing overthrow in the advance thereof.

18. In a calculating machine, a dial, a column of keys, actuating meansoperative in response to the down strokes of the keys to advance thedial and including a rock shaft common to the keys of said column, stopsadapted to arrest said shaft at different points in its rotation, andmeans set by the different keys of the column for controlling saidstops.

7 19. In a calculating machine, a dial, a column of keys, meansoperative in response to the down stroke of said keys for advancing thedial, said means including a shaft common to the keys of the column, aset of stops column and adapted to differentially limit the extent ofrotation of said shaft, and means controlled by the different keys forsetting the respective stops in operative condition.

20. In a calculating machine, a dial, a colv umn of keys, meansoperative in response to the down strokes of said keys for advancing thedial, said means including a shaft com- 20 mon to the keys of thecolumn, a set of stop arms fixed in different angular positions on saidshaft and corresponding to the respective keys, and a set of stops eachmovable into the path of its corresponding stop arm upon the down strokeof the respective key.

21. In a calculating machine, a dial, a key, dial actuating meansoperative in response to the down stroke of such key to advance thedial, said means including a shaft, a

stop arm fixed to said shaft, and a stop movable into the path of saidstop arm in response to the initial part of the down stroke of such key.

22. In a calculating machine, a dial, a key having a'stem, dialactuating means operative in response to a stroke of such key to advancethe dial, said actuating means carrying a stop to limit its dialadvancing movement, and an overthrow means normally located in the pathof said key stem and set into operative relation with the stop means bysaid stem in consequence of the initial part of a stroke of such key andheld in such relation by the key stem during the subsequent dialactuating move ment of the key.

In testimony whereof I have hereunto set my hand in presence of tWosubscribing Witnesses.

JAMES F. MAYS. Witnesses:

C. A; BATEMAN, CHAS. S. HYER.

Copies of this patent may be obtained for five cents each, by addressingthe "Commissioner of Patents, Washington, D. 0."

